rp-pppoe: move from meta-oe to meta-networking and tweak

* Move packaging definitions to the end
* Move SRC_URI checksums next to SRC_URI
* Set SUMMARY instead of DESCRIPTION

Signed-off-by: Paul Eggleton <paul.eggleton@linux.intel.com>
Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>